1. Technical Field
The present invention relates to a waterproof structure for an overhead wire tension balancer and to a technique in which the structure can be used.
2. Background Art
As a device for applying appropriate tension to an overhead wire of railroad, an overhead wire tension balancer having a coil spring has been disclosed (See reference 1). The overhead wire tension balancer has a structure in which plural cylinders are coaxially arranged, and tension is generated because of elasticity of the spring in the case in which the inner cylinder is pulled out of the outer cylinder. Therefore, it must have a structure in which the outer cylinder and the inner cylinder are relatively movable. Since there may be a case in which rainwater enters into the gap between the outer cylinder and the inner cylinder, it has a water draining structure such as a water drainage hole, gap or the like.
In the overhead wire tension balancer, a coil spring is contained so as to apply tension to the overhead wire. Since the spring is in frictional contact with the inner surface of the cylinder or the outer surface of the inner cylinder during above-mentioned movement of the cylinders, a grease as a lubricating agent is applied on a contacting portion of the coil spring and the cylinder.
The reference mentioned above is Japanese Unexamined Patent Application Publication No. Heisei 11 (1999)-48834.